Crown K80604-0 Studio Reference Professional Studio Amplifiers Owner’s Manual
- June 13, 2024
- CROWN
Table of Contents
- Crown K80604-0 Studio Reference Professional Studio Amplifiers
- Product Information
- Welcome
- Facilities
- Installation
- Operation
- Technical Information
- Specifications
- AC Power Draw and Thermal Dissipation
- Accessories
- Service
- THREE YEAR FULL WARRANTY
- Read User Manual Online (PDF format)
- Download This Manual (PDF format)
Crown K80604-0 Studio Reference Professional Studio Amplifiers
Product Information
The Studio ReferenceTM Professional Studio Amplifiers are products manufactured by the Professional Audio Division of Crown International, Inc. In select countries, they are exported under the name Amcron. These amplifiers are designed for professional audio applications and provide high-quality sound reproduction. The amplifiers come with a three-year full warranty, which covers any failure of the product that occurs within the warranty period. The warranty is valid worldwide, except for certain exclusions mentioned below. Please note that if your unit bears the name Amcron, you should substitute it for the name Crown in this warranty.
Warranty Exclusions
The Crown Warranty does not cover any product that has been damaged due to
intentional misuse, accidents, negligence, or losses covered under insurance
contracts. Additionally, the warranty does not apply if the serial number has
been defaced, altered, or removed.
Obtaining Warranty Service If you require warranty service, you must notify
us within ninety (90) days after the expiration of the warranty period. All
components must be shipped in a factory pack. Our authorized service center
will take corrective action within a reasonable time upon receipt of the
defective product. In case you are not satisfied with the repairs made by our
authorized service center, please notify them immediately.
Disclaimer of Damages
You are not entitled to recover any incidental damages resulting from any
defect in the new Crown product. This includes damages to other products
resulting from such a defect.
Warranty Alterations
No person has the authority to enlarge, amend, or modify this Crown Warranty.
The length of time you are deprived of using the new Crown product does not
extend the warranty. Repairs and replacement parts provided under this
warranty will only carry the unexpired portion of the warranty.
Design Changes
We reserve the right to change the design of our products without notice and
with no obligation to make corresponding changes in previously manufactured
products.
The information furnished in this manual does not include all of the details of design, production, or variations of the equipment. Nor does it cover every possible situation that may arise during installation, operation or maintenance. If your unit bears the name “Amcron,” please substitute it for the name “Crown” in this manual. If you need special assistance beyond the scope of this manual, please contact our Technical Support Group.
Crown Audio Division Technical Support Group
57620 C.R. 105, Elkhart, Indiana 46517 U.S.A.
Phone: 800-342-6939 (U.S.A.) or
219-294-8200 Fax:
219-294-8301
IMPORTANT
STUDIO REFERENCE AMPLIFIERS REQUIRE CLASS 1 OUTPUT WIRING.
CAUTION
TO PREVENT ELECTRIC SHOCK DO NOT REMOVE TOP OR BOTTOM COVERS. NO USER-
SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
DISCONNECT POWER CORD BEFORE REMOVING REAR INPUT MODULE TO ACCESS GAIN SWITCH.
WARNING
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR
MOISTURE!
Unpacking Instructions
Please unpack and inspect your new amplifier for any damage that may have
occurred during transit. If damage is found, notify the transportation company
immediately. Only you, the consignee, may initiate a claim for shipping
damage. Crown will be happy to cooperate fully as needed. Save the shipping
carton as evidence of damage for the shipper’s inspection.
Even if the unit arrived in perfect condition, as most do, save all packing materials so you will have them if you ever need to transport the unit. NEVER SHIP THE UNIT WITHOUT THE FACTORY PACK.
Welcome
The stunning realism you will experience when listening to a Crown Studio Reference™ amplifier will redefine your expectations. The evolution of this studio standard ushers in a new era of powerful, ultraquiet amplifiers capable of faithfully reproducing the most demanding signals that state-of-the-art 20-bit digital recording systems can offer. This kind of sonic integrity does not happen accidentally. It demands the leadership and technical excellence for which Crown has long been known. With the best transfer function in the industry, ultra-high dynamic range and extraordinary damping factor, your Studio Reference amplifier comes closer to the ideal “straight wire with gain” than any other amplifier. As you listen, it will become apparent—the amplifier’s low-frequency transient response is the standard by which all others must be judged. We have taken great care at every step in the creation of your amplifier—from the selection of its components to the routing of each wire. It is our goal to provide you with total satisfaction. This is one reason why we have spent considerable effort in providing you with the most complete Owner’s Manual in the business. Please read it carefully—especially the instructions, warnings and cautions. It will help you successfully install and use your new amplifier. Be sure to read Sections 3.3.2 and 3.3.3 if you plan to use one of the amplifier’s two mono modes. Please send in your warranty registration card today and save your bill of sale because it is your official proof of purchase. We hope you enjoy your new amplifier, and thank you for choosing Crown.
Features
Studio Reference amplifiers integrate several cutting-edge technologies that
make them the most accurate reference amplifiers available. For example, in
Stereo mode each channel can actually be treated as a sepa-rate amplifier
because of its separate high-voltage power supplies and ultra-low crosstalk.
Here are some of its many impressive features:
- Crown’s unconventional grounded bridge™ circuitry delivers incredible voltage swings without using stressful output transistor configurations like other more traditional amplifiers. This results in significantly lower distortion and superior reliability.
- Patented ODEP ® (Output Device Emulation Protection) circuitry detects and compensates for overheating and overload to keep the amplifier working when others would fail.
- IOC ® (Input/Output Comparator) circuitry immediately alerts you of any distortion that exceeds 0.05% to provide dynamic proof of distortion-free performance.
- P.I.P. (Programmable Input Processor) connector accepts accessories that tailor your amplifier to suit specific applications.
- Extremely wide dynamic range capable of accurately reproducing 20-bit digital recordings.
- Ultra-high damping factor delivers superior loudspeaker motion control for the cleanest, tightest, chest-thumping bottom end you’ve ever felt—or heard.
- Super-low harmonic and intermodulation distortion give your amplifier the best transfer function in the business.
- Two mono modes (Bridge-Mono and Parallel-Mono) for driving a wide range of load impedances.
- Custom-designed, tape-wound, low-noise toroidal supplies with extremely high power density.
- High-voltage headroom and high-current headroom provide energy reserves that make it easy to drive low-impedance loads and highly reactive loads to full power.
- Full protection against shorted outputs, mismatched loads, general overheating, DC and high-frequency overloads. Full overvoltage and internal fault protection.
- Indicators include Enable, ODEP, IOC, Signal Presence and the Dynamic Range/Level meter.
- Balanced phone jacks and XLR connectors are provided for input. Two pair of 5-way binding posts per channel are provided for versatile output connection.
- Ground lift switch isolates the AC power and phone jack audio grounds.
- Efficient heat sinks and a self-contained, on-demand, infinitely variable forced-air cooling system prevents overheating and prolongs component life.
- Internal three-position input sensitivity switch provides settings of 0.775 volts and 1.4 volts for standard 1 kHz power, and 26 dB gain.
- Mounts in a standard 19 inch (48.3 cm) equipment rack, or units can be stacked directly on top of each other.
- Three-year “No-Fault” full warranty completely protects your investment and guarantees its specifications.
Facilities
A. Level Controls
Each channel’s output level can be adjusted accurately using the 31-position detented level controls on the front panel (see Section 4.4).
B. ODEP Indicators
During normal operation of the amplifier, the ODEP (Output Device Emulation
Protection) indicators glow brightly to show the presence of reserve
thermodynamic energy. They dim proportionally as energy reserves decrease. In
the rare event that energy re-serves are depleted, the indicators turn off and
ODEP proportionally limits the output drive so the amplifier can safely
continue operating even under severe conditions. These indicators also help to
identify more unusual op-erating conditions (see Figure 4.2).
C. IOC Indicators
The IOC (Input Output Comparator) indicators serve as sensitive distortion
indicators to provide proof of distortion-free performance. Under normal
conditions, the indicators remain off. They flash if the output waveform
differs from the input by 0.05% or more (see Section 4.2). If the input signal
level is too high, the indicators will also flash brightly with a half-second
hold delay to show input overload or output clipping.
Note: The channel 2 IOC indicator stays on in Parallel-Mono mode. See
Section 4.2.
D. Signal Presence Indicators
These indicators flash synchronously with the amplifier’s audio output to show
signal presence.
Note: These indicators may not flash at very low input signal levels. See
Section 4.2.
E. Enable Indicator
This indicator lights when the amplifier has been “enabled” or turned on, and
AC power is available.
F. Enable Switch
This push button is used to turn the amplifier on and off. When turned on, the
output is muted for about four seconds to protect your system from start-up
transients. This is why a power sequencer is rarely needed for multiple units.
(The turn-on delay can be changed. Contact Crown’s Technical Support Group for
details.)
G. Dust Filter
The dust filter removes large particles from the air drawn in by the cooling
fan. In most cases, the fan will not run so the filter will remain clean. If
the filter becomes dirty, it can be removed for easy cleaning (see Section
4.5).
H. Dynamic Range/ Level Meters
A five-segment output meter is provided for each channel. The meters are
factory-set to show the dynamic range of the signals in dB, which is computed
as the ratio of peak to average output power. Also, the meter can optionally
be set to show output levels (see Section 4.4).
Meter Switches
Two switches behind the front panel can be used to customize the output
meters (H). By default, the meters display dynamic range. To make the meters
display signal levels or to turn them off, see Section 4.4.
I. Reset Switch
This back panel switch can be used to trip and reset the AC mains circuit
breaker (see Section 4.3.4).
J. Power Cord
For 120 VAC, 60 Hz North American units, the Studio Reference / includes a 10
AWG power cord and NEMA TT30P plug, and the Studio Reference // includes a 12
AWG cord and NEMA 5-15P plug. Other units are shipped with an appropriate
power cord and plug.
K. P.I.P. Module
The standard P.I.P.-FX input module is provided with your amplifier. It
provides female XLR input connectors. Each pair of XLR and phone jack
connectors is wired in parallel so the unused connector can be used as a
“daisy chain” output to connect a source to multiple amplifiers. Other P.I.P.
modules can be used in place of the P.I.P.-FX to provide additional features
that customize your amplifier for different applications (see Section 8 for
available P.I.P. modules).
L. Balanced XLR Inputs
A balanced three-pin female XLR connector is provided on the P.I.P.-FX (K) for
input to each channel. Caution: Do not use the channel 2 input in either mono
mode.
M. Output Connectors
Two pairs of versatile 5-way binding posts are provided for the output of each
channel so multiple loudspeakers can be connected easily. They accept banana
plugs, spade lugs or bare wire.
N. Stereo/Mono Switch
This switch is used to select one of three operating modes. Stereo mode is
used for normal two-channel operation, Bridge-Mono mode is used to drive a
single channel with a load impedance of at least 4 ohms, and Parallel-Mono
mode is used to drive a single channel with a load impedance of less than 4
ohms. WARNING: Turn off the amplifier before changing this switch (see Section
3.3).
O. Balanced Phone Jack Inputs
A balanced 1¦4-inch phone jack is provided for input to each channel. They may
be used with either balanced (tip, ring and sleeve) or unbalanced (tip and
sleeve) input wiring (see Section 3.3). These inputs are in parallel with the
P.I.P. connector, so they should not be used as inputs if the installed P.I.P.
has active circuitry. Caution: Do not use the channel 2 input in either mono
mode.
P. Ground Lift Switch
The input signal ground may be isolated from the AC ground with this switch to
help prevent unwanted ground loops. It affects only the phone jacks (O). It
has no affect on the P.I.P. module’s XLR connectors. Activating the switch
inserts an impedance between the sleeve of each phone input jack and the
circuit ground.
Input Sensitivity Switch
The three-position input sensitivity switch inside the amplifier can be
accessed by removing the P.I.P. module. Settings include 0.775 volts and 1.4
volts for rated output, and 26 dB voltage gain (see Section 4.4).
Installation
Mounting
Studio Reference amplifiers are designed for standard 19-inch (48.3 cm) rack
mounting or stacking without a cabinet. In a rack, it is best to mount units
directly on top of each other. This provides the most efficient airflow and
support. If the rack will be transported, we recommend that you fasten the
amplifier’s back panel securely to the rack to help support the unit’s weight.
Before proceeding, make sure the meter switches are set to your liking. The front panel assembly must first be removed to change these switches, so it is easier to do before the unit is mounted (see Section 4.4). By now, you may be looking for rack ears. The rack ears are covered by two attractive end caps which are held in place by phillips screws (see Figure 3.2). To use the rack ears, remove the screws and lift off the caps. With sufficient side clearance, you can reinstall the end caps once the amplifier is mounted in the rack.
Cooling
Your amplifier has an internal variable speed fan that is controlled to match
the unit’s real-time cooling needs. With proper installation and typical
studio use, the fan may never need to run. For best results, you should
familiarize yourself with its cooling requirements. Here are some tips to help
keep your amplifier cool. First, never block the amplifier’s front or side air
vents. If the amplifier is rack-mounted, its sides should be at least 2 inches
(5 cm) away from the cabinet (see Figure 3.3). Also, open rack spaces should
be covered to prevent heated air from the side vents from being drawn out the
front of the rack into the front air intake. You will know when your Studio
Reference amplifier has sufficient cooling because its ODEP indicators will be
brightly lit. If the amplifier’s ODEP indicators dim or turn off, overly
demanding conditions are forcing it to protect itself from overheating. If you
experience a cooling problem, you should consider several factors that may be
contributing to the problem, including load impedance, airflow and ambient air
temperature. Low-impedance loads generate more heat than higher-impedance
loads. To avoid impedance-related cooling problems, connect loads to each
channel with a total impedance of at least 2 ohms in Stereo, 4 ohms in Bridge-
Mono, and 1 ohm in Parallel-Mono mode (see Section 3.3 for wiring
instructions). If your loads are reasonable and you still have a cooling
problem, check for shorts in the loudspeaker cables, and look for problems
with airflow or ambient air temperature. Airflow restrictions are the most
common cause of inadequate cooling. Restrictions may result from improper
mounting, piles of power cords, clogged dust filters and closed rack doors.
Mount your amplifier to allow sufficient air flow into the front intake, out
the side exhaust vents, and out the back of the rack. An airflow restriction
like a pile of power cords can simply be moved out of the way. Air filters
should be cleaned using the procedure in Section 4.5. If rack doors are the
problem, you can leave them open, remove them, or install a grille. If you
install a grille, we recommend using a wire grille because perforated panels
restrict airflow by at least 40%.
If your ODEP indicators still dim under demanding conditions, we recommend
that you check the table of indicator states in Figure 4.2 to eliminate other
conditions that could be the source of the problem. If it is clear that the
amplifier does not have sufficient air flow, you may want to install
supplemental cooling like a rack-mounted blower or an air conditioner.
A “squirrel cage” blower can be installed at the bottom of the rack so it
blows outside air into the space between the door and the front of the
amplifiers. This will pressurize the “chimney” behind the door (Figure 3.4,
Option 1). The blower should not blow air into or take air out of the space
behind the amplifiers. For racks without a front door, you can evacuate the
rack by mounting the blower at the top of the rack so air blows out the back
(Figure 3.4, Option 2). You can estimate a rack’s required airflow by adding
each unit’s maximum airflow rating. The Studio Reference / and // can each
move up to 45 cubic feet (1.3 cubic meters) of air per minute. So if you put
one of each in a rack, you would need 90 cubic feet (2.5 cubic meters) of
airflow through the rack per minute under worst-case conditions (45 cubic feet
- 45 cubic feet = 90 cubic feet).
Another way to increase cooling is to use air conditioning. It is rarely a necessity because internal fans and rack-mounted blowers almost always provide enough airflow for the most extreme conditions. Still, air conditioning helps reduce the ambient temperature of the air flowing through the rack. If you plan to use air conditioning, refer to Section 7 for information on calculating the hourly thermal dissipation of your system.
Wiring
Figures 3.5 through 3.7 show common ways to set up a Studio Reference
amplifier. Input and output connectors are located on the back panel. Be
careful when making connections, selecting sources and controlling output
levels. The load you save may be your own! Crown is not responsible for
damaged loads that result from carelessness or deliberate overpowering.
CAUTION: Always disconnect the AC power and turn the level controls down
when making or breaking connections. This practice reduces the chance of loud
blasts that can cause loudspeaker damage.
Studio Reference amplifiers provide three operating modes: Stereo, Bridge-Mono
and Parallel-Mono. Stereo mode provides standard two-channel operation;
Bridge-Mono provides a single channel with double the output voltage of Stereo
mode; and Parallel-Mono mode provides a single channel with double the output
current of Stereo mode. These modes can be selected using the stereo/mono
switch on the back panel. Each mode is wired differently, so be sure to note
any special wiring requirements for the mode you will be using.
Stereo (Two-Channel) Operation
Stereo mode installation is very intuitive: input channel 1 feeds output
channel 1, and input channel 2 feeds output channel 2. To put the amplifier
into Stereo mode, turn it off, slide the stereo/mono switch to the center
position, and properly connect the output wiring as shown in Figure 3.5. Each
output channel has two sets of binding posts to make it easier for you to
connect multiple loudspeaker cables to each channel. Be sure to observe
correct loudspeaker polarity (see Figure 3.5) and be careful not to short the
outputs.
CAUTION: In Stereo mode, never tie an amplifier’s outputs together
directly, and never parallel them with the output of another amplifier. Such
connections do not result in increased output power, but may activate the
protection circuitry to prevent overheating.
Bridge-Mono Operation
Bridge-Mono mode is used to drive loads with a total impedance of at least 4
ohms (see Parallel-Mono if the load is less than 4 ohms). Wiring for the
Bridge-Mono mode is different from the other modes and requires special
attention. First, turn off the amplifier. Then select Bridge-Mono mode by
sliding the stereo/mono switch to the right (as you face the back panel). Both
outputs receive the channel 1 input signal, but channel 2 is inverted so it
can be bridged with channel 1. Do not use the channel 2 input or signal
quality will be greatly degraded. Also, turn down the channel 2 level control
(fully counterclockwise).
Note: The channel 2 input and level control are not de-feated in Bridge-
Mono mode. Any signal feeding channel 2 will work against the channel 1
signal, and usually results in distortion and inefficient operation. Connect
the load across the two red (+) binding posts (see Figure 3.6). The positive
(+) loudspeaker lead connects to the red channel 1 binding post, and the
negative (–) or ground lead from the loudspeaker connects to the red channel 2
binding post. Do not connect the black binding posts (–). Also, the load must
be balanced (neither side shorted to ground).
CAUTION: Only connect balanced equipment (meters, switches, etc.) to the
Bridge-Mono output. Both sides of the line must be isolated from the input
grounds or oscillations may occur.
Parallel-Mono Operation
Parallel-Mono mode is used to drive loads with a total impedance of less than
4 ohms (see Bridge-Mono if the load is 4 ohms or more). Wiring for Parallel-
Mono mode is very different from the other modes and requires special
attention.
To select Parallel-Mono mode, turn off the amplifier and slide the stereo/mono
switch to the left (as you face the back panel). Connect the input signal to
channel 1 only. The channel 2 input and level control are bypassed in this
mode, so they should not be used.
Note: It is normal for the channel 2 IOC indicator to stay on in
Parallel-Mono mode.
Connect the load to the channel 1 output as shown in Figure 3.7. The positive
(+) lead from the loudspeaker connects to the red channel 1 binding post, and
the negative (–) or ground lead from the loudspeaker connects to the black
channel 1 binding post. Finally, install a jumper wire of at least 14 gauge
between the channel 1 and channel 2 red binding posts.
CAUTION: When Parallel-Mono wiring is installed, do not attempt to
operate in Stereo or Bridge-Mono mode until the wiring is removed (especially
the jumper wire). Failure to do so will result in high distortion and
excessive heating.
Input Connection
The balanced inputs have a nominal impedance of 10 K ohms (5 K ohms
unbalanced) and will accept the line-level output of most devices. Phone jacks
are provided on the back panel, while the factory-installed P.I.P.-FX provides
female XLR input connectors (see Figure 2.2). Optional P.I.P. modules like the
P.I.P.-BB and the P.I.P.-FPX can provide barrier block and phono (RCA)
connectors. Various P.I.P.s are also available which provide a wide range of
input signal processing features (see Section 8).
Correct input wiring depends on two factors:(1) whether the input signal is
balanced or unbalanced, and (2) whether the signal floats or has a ground
reference. Figures 3.8 and 3.9 show the recommended connection techniques for
each combination of source signal characteristics.
The amplifier’s built-in 1¦4-inch input phone jacks can be wired similarly for balanced or unbalanced, floating or ground-referenced sources. They have a standard tip-ring-sleeve (TRS) configuration: the tip is positive (+), the ring is negative (–) and the sleeve is ground (see Figure 3.10). Wiring for various sources follows the XLR wiring examples in Figures 3.8 and 3.9. If you install a P.I.P. module other than the P.I.P.-FX, P.I.P.-BB, P.I.P.-FMX or P.I.P.-FPX, do not connect input signals to the phone jacks. The phone jacks are in parallel with the output of the P.I.P. module, so the source connected to the phone jacks can feed into the P.I.P. and generate a distortion in the output. The phone jacks can still be used as “daisy chain” outputs to feed the post-processed signal from the P.I.P. to the input of other amplifiers. If the amplifier will be used in Bridge-Mono or Parallel-Mono mode, be sure to follow the instructions provided in Sections 3.3.2 and 3.3.3. Do not use the channel 2 input in either mono mode.
SOLVING INPUT PROBLEMS
Sometimes large subsonic (subaudible) frequencies are present in the input
signal. These can damage loudspeakers by overloading or overheating them. To
attenuate such frequencies, place a capacitor in series with the input signal
line. The graph in Figure 3.11 shows some capacitor values and how they affect
the frequency response of a Studio Reference amplifier. Use only low-leakage
capacitors.
Another problem to avoid is large levels of radio frequencies or RF in the input signal. Although high RF levels may not pose a threat to the amplifier, they can burn out tweeters or other loads that are sensitive to high frequencies. Extremely high RF levels can also cause your amplifier to prematurely activate its protection circuitry, resulting in inefficient operation. RF can be introduced into a signal by local radio stations and from the bias signal of many tape recorders. To prevent high levels of input RF, install an appropriate low-pass filter in series with the input signal. Some examples of unbalanced wiring for low-pass filters are shown in Figure 3.12.
For balanced input wiring, use an example from Figure 3.13. Filters A, B and C correspond to the unbalanced filters shown in Figure 3.12. Filter D also incorporates the subsonic filter in Figure 3.11.
Tip: The P.I.P.-FX has plenty of space on its circuit board for the
addition of input filter circuitry.
Another problem to avoid is ground loops. These are undesired currents that
flow in a grounded system and usually cause hum in the output. A common source
of ground loop problems is the placement of input cables parallel to power
cables or near power transformers. The magnetic field that surrounds these
conductors can induce the 50 or 60 Hz alternating current into your input
cables. To prevent this type of ground loop, it is always a good idea to
locate input cables away from power cables and power transformers. We also
recommend using shielded or twisted pair wire. With loose wires, use tie-wraps
to bundle together each pair of input wires. This helps reduce magnetically
induced current by minimizing the cross-sectional area between conductors that
could bisect the magnetic field. Ground loops often occur when the input and
output grounds are tied together. DO NOT CONNECT THE INPUT AND OUTPUT GROUNDS
TOGETHER. Tying the grounds together can also cause feedback oscillation from
the load current flowing in the loop. To avoid this problem, use proper
grounding, isolate the inputs, and isolate other common AC devices. When using
the input phone jacks, the signal grounds can be isolated from the AC mains
ground with the ground lift switch located on the amplifier’s back panel (see
Figure 2.2 and Section 4.4).
Output Connection
Consider the rated power-handling capacity of your load before connecting it
to the amplifier. Crown is not liable for damage incurred at any time due to
overpowering. Fusing loudspeaker lines is highly recommended (see Section
3.3.6). Also, please pay close attention to Section 4.1, Precautions. You
should always install loudspeaker cables of sufficient gauge (wire thickness)
for the length used. The resistance introduced by inadequate output wiring
will reduce the amplifier’s power to and motion control of the loudspeakers.
The latter problem occurs because the damping factor decreases as the cable
resistance increases. This is very important because the amplifier’s excellent
damping factor can be easily negated by using an insufficient cable. Use the
nomograph in Figure 3.14 and the procedure that follows to find the
recommended wire gauge (AWG or American Wire Gauge) for your
system.
-
For loads connected in parallel, use the equation that follows to calculate each channel’s total load resistance. Substitute the rated impedance of the connected loudspeakers for the Zs in the equation. When finished, mark your answer on the nomograph’s “Load Resistance” line.
Total Load Resistance in Ohms = (1¦Z1 + 1¦Z2 + 1¦Z3…)–1 -
Select an acceptable damping factor and mark it on the “Damping Factor” line. Your amplifier can provide a phenomenal damping factor of 20,000 from 10 to 200 Hz in Stereo mode with an 8 ohm load. In contrast, most other amplifiers have a damping factor rating of 200 or less. Higher damping factors yield lower distortion and greater motion control over the loudspeakers. To give you a basis for comparison, effective damping factors for commercial applications typically run between 50 and 100. Higher damping factors may be desirable for live sound, but long cable lengths often limit the highest damping factor that can be achieved practically. (Under these circumstances, Crown’s IQ System is often used so amplifiers can be easily monitored and controlled when they are located very near the loudspeakers.) In recording studios and home hi-fi, a damping factor of 500 or more is very desirable.
-
Draw a line through the two points with a pencil, and continue until it intersects the “Source Resistance” line.
-
On the “2-Cond. Cable” line, mark the length of the cable run.
-
Draw a pencil line from the mark on the “Source Resistance” line through the mark on the “2-Cond. Cable” line, and on to intersect the “Annealed Copper Wire” line.
-
The required wire gauge for the selected wire length and damping factor is the value on the “Annealed Copper Wire” line. Note: Wire size increases as the AWG gets smaller.
-
If the size of the cable exceeds what you want to use, (1) find a way to use shorter cables, like using the IQ System, (2) settle for a lower damping factor, or (3) use more than one cable for each line. Options 1 and 2 will require the substitution of new values for cable length or damping factor in the nomograph. For option 3, estimate the effective wire gauge by subtracting 3 from the apparent wire gauge every time the number of conductors of equal gauge is doubled. So, if #10 wire is too large, two #13 wires can be substituted, or four #16 wires can be used for the same effect.
SOLVING OUTPUT PROBLEMS
High-frequency oscillations can cause your amplifier to prematurely activate
its protection circuitry. The effects of this problem are similar to the
effects of the RF problem described in Section 3.3.4. To prevent high-
frequency oscillations, follow these guidelines:
- When using long cable runs, or when different amplifiers share a common cable tray or jacket, use tie-wraps to bundle individual conductors so the wires for each loudspeaker are kept close together. (Do not bundle wires from different amplifiers.) This reduces the chance of conductors acting like antennas to transmit or receive the high frequencies that can cause oscillation.
- Avoid using shielded loudspeaker cable.
- Never tie together input and output grounds.
- Never tie together the output of different amplifiers.
- Keep output cables separated from input cables.
- Install a low-pass filter in series with each input (see Section 3.3.4).
- Install the input wiring according to the instructions in Section 3.3.4.
Another problem to avoid is the presence of large subsonic currents when
primarily inductive loads are used. Examples of inductive loads are 70-volt
step-up transformers and electrostatic loudspeakers.
Inductive loads can appear as a short circuit at low frequencies. This can
cause the amplifier to produce large low-frequency currents and activate its
protection circuitry. Always take the precaution of installing a high-pass
filter in series with the amplifier’s input when inductive loads are used. A
three-pole, 18 dB per octave filter with a –3 dB frequency of 50 Hz is
recommended (some applications may benefit from an even higher –3 dB
frequency). Such a filter is described with the subsonic frequency problems in
Section 3.3.4.
Another way to protect inductive loads from large low-frequency currents and
prevent the amplifier from pre-maturely activating its protective systems is
to parallel a 590 to 708 oF nonpolarized motor start capacitor and 4-ohm, a
20-watt resistor in series with the amplifier output and the positive (+)
transformer lead. This circuit is shown in Figure 3.15. It uses components
that are available from most electrical supply stores.
Additional Load Protection
Studio Reference amplifiers can deliver very high power levels, so it’s a good
idea to add protection for your loudspeakers if it is not built-in.
Loudspeakers are subject to thermal damage from sustained overpowering and
mechanical damage from large transient voltages. In both cases, fuses may be
used to protect your loudspeakers, or you may opt for the convenience of a
P.I.P. module that provides similar protection.
Thermal protection and voltage protection require different types of fuses.
Slow-blow fuses are used to prevent thermal damage because they respond to
thermal conditions like a loudspeaker. High-speed instrument fuses like the
Littlefuse 361000 series are used to protect loudspeakers from transient
voltages. The nomo-graph in Figure 3.16 can be used to select the correct fuse
for thermal or voltage protection.
There are two common ways to install the fuses. One approach is to put a
single fuse in series with each output. This is easy because there is only one
fuse per channel to install. But if the fuse blows, power is removed to all of
the connected loads.
A better approach is to fuse each driver independently. This allows you to
apply the most appropriate protection for the type of driver being used. In
general, low-frequency drivers (woofers) are most susceptible to thermal
damage and high-frequency drivers (tweeters) are usually damaged by large
transient voltages. This means that your loudspeakers will tend to have better
protection when the woofers are protected by slow-blow fuses and high-
frequency drivers are protected by high-speed instrument fuses.
Depending on the application, you may want to use a specialized P.I.P. module
to protect your loudspeakers. Again, some modules are more appropriate for
long-term thermal protection, while others are more appropriate for protection
against transients. A Smart Amp™ IQ-P.I.P. module is most commonly used for
long-term loudspeaker thermal protection. Each Smart Amp channel provides an
independent “smooth output limiter” that controls average output levels over
time while it allows transients to pass.
Most of the other P.I.P. modules that provide signal-driven compression can be
used to prevent loud-speaker damage from transient voltage. These modules
include the P.I.P.-AMCb, P.I.P.-EDCb and P.I.P.-PA. While the P.I.P.-EDCb is
most commonly used for general loudspeaker protection, the P.I.P.-AMCb is very
popular in systems that require a high-quality crossover, and the P.I.P.-PA is
the process of choice for applications that require a microphone and line
level input for each channel. And finally, the Smart Amp IQ-P.I.P.-DP provides
both an input com-pressor for transient protection and a smooth output limiter
for long-term thermal protection. For more information on P.I.P. modules, see
Section 8.
AC Mains Power
All Studio Reference amplifiers are shipped with an appropriate line cord and
plug. The 120 VAC, 60 Hz North American Studio Reference / has a special TT30P
plug and includes a matching receptacle. Always use an isolated power
receptacle whenever possible with adequate voltage and current. Excessive line
voltages 10% or higher above the rated voltage will cause the amplifier to
activate its standby mode (see Section 4.3.2). For example, do not exceed a
132 VAC with models rated for 120 VAC operation.
Unless otherwise noted, all specifications in this manual were measured using
120 VAC, 60 Hz power mains with voltage accurate to within 0.5% and THD of
less than 1.0% under all test conditions. Performance variations can occur at
other AC mains voltages and line frequencies. Line regulation problems will
directly affect the output power available from the amplifier.
Operation
Precautions
Although your amplifier is protected from internal and external faults, you
should still take the following precautions for optimum performance and
safety:
- Improper wiring for the Stereo, Bridge-Mono or Parallel-Mono modes can result in serious operating difficulties (see Sections 3.3.1 through 3.3.3).
- When driving an inductive load like an electrostatic loudspeaker, use a high-pass filter or protective network to prevent premature activation of the amplifier’s protection circuitry (see Section 3.3.4).
- WARNING: Do not change the position of the stereo/mono switch unless the amplifier is first turned off.
- CAUTION: In Parallel-Mono mode, a jumper must be installed between the channel 1 and 2 red (+) binding post outputs. Be sure to remove this jumper for Stereo or Bridge-Mono modes, otherwise high distortion and excessive heating will occur. Check the stereo/mono switch on the back panel for proper position.
- Turn off the amplifier and unplug it from the AC mains before removing the amplifier’s P.I.P. model or dust filter.
- Use care when making connections, selecting signal sources and controlling the output level. The load you save may be your own!
- Do not short the ground lead of an output cable to the input signal ground. This will form a ground loop and may cause oscillations.
- Operate the amplifier from AC mains of not more than 10% above or below the selected line voltage and only at the rated line frequencies.
- Never connect the output to a power supply output, battery or power main. Such connections may result in electrical shock.
- Tampering with the circuitry by unqualified personnel, or making unauthorized circuit changes may be hazardous and invalidate all agency listings.
Remember: Crown is not liable for damage that results from overdriving other system components.
Indicators
The front panel has several helpful indicators. The en-able indicator is
provided to show the amplifier has been turned on (or enabled) and that its
low-voltage power supply and on-demand forced air cooling system are working.
It does not indicate the status of the high-voltage power supplies. For
example, the enable indicator will stay on in the improbable event that one or
both channels overheat causing an internal shutdown of the high-voltage
supplies.
The green ODEP indicators confirm the normal operation of Crown’s patented
Output Device Emulation Pro-tection circuitry. During normal operation, they
glow brightly to confirm the presence of reserve thermodynamic energy. They
dim proportionally as the energy reserve decreases. In the rare event that
there is no reserve, the indicators will turn off and ODEP will pro-
portionally limit the drive level of the output stages so the amplifier can
continue safe operation even when the operating conditions are severe. (For a
more detailed description of ODEP, see Section 4.3.1.)
A channel’s ODEP indicator also turns off if its high-voltage power supply is
put in “standby” mode or the amplifier’s circuit breaker is tripped. The
standby mode is activated if DC or heavy common-mode current is detected in
the output, if the transformer thermal protection system is activated, if a
P.I.P. like the Smart Amp IQ-P.I.P. is used to shut down a high-voltage
supply, or if excessive AC mains voltage is detected. For more information see
Section 4.3 and the table in Figure 4.2. The yellow IOC indicators act as
sensitive distortion meters to provide proof of distortion-free performance.
The IOC (Input/Output Comparator) circuitry compares the incoming signal’s
waveform to that of the output. Any difference between the two is distortion.
The IOC indicators flash if there is a difference of 0.05% or more. The IOC
indicators also show input overload by flashing brightly with a half-second
hold delay. It is normal for them to light momentarily when the amplifier is
first turned on.
Note: The channel 2 IOC indicator will stay on in Parallel-Mono mode.
Also, an IOC indicator will stay on in abnormal situations where a high-
voltage power supply is temporarily put in standby mode.
The green signal presence indicators flash synchronously with the amplifier’s
output signal. The signal detector is connected to the signal path after the
input gain stages and level controls, so a flashing indicator tells you that
there is audio in and out of the amplifier.
Note: The signal presence indicators may not report signal presence if
the output signal level is too low.
The dynamic range /level meters are five-segment output meters that can be set
to monitor either the dynamic range or the level of the output signal. They
are factory-set to show dynamic range. A switch located behind the front panel
is used to select the meter dis-play mode (see Section 4.4 for complete
instructions).
As dynamic range meters they show each channel’s ratio of peak-to-average power in dB. The dynamic range may be low for sources like AM/FM radio or low- quality recordings. Other sources like live music or high-quality recordings may be much higher. As out-put level meters they show how high the output levels are in dB relative to full power. At 0 dB, the unit is delivering full standard 1 kHz power (see Section 6).
Protection Systems
Studio Reference amplifiers provide extensive protection and diagnostics
capabilities. Protection systems include ODEP, standby mode, an AC circuit
breaker and transformer thermal protection. These systems will prevent
amplifier damage in virtually any situation.
ODEP
Crown invented ODEP to solve two long-standing problems in amplifier design:
to prevent amplifier shut-down during demanding operation and to increase the
efficiency of the output circuitry.
To do this, Crown established a rigorous program to measure the safe operating
area (SOA) of each output transistor before installing it in an amplifier.
Next, Crown designed intelligent circuitry to simulate the instantaneous
operating conditions of the output transistors. Its name describes what it
does: Output Device Emulation Protection or ODEP. In addition to simulating
the operating conditions of the output transistors, it also compares their
operation to their known SOA. If ODEP sees that more power is about to be
asked of the output transistors than they are capable of delivering under the
present conditions, ODEP immediately limits the drive level until it falls
within the SOA. Limiting is proportional and kept to an absolute minimum—only
what is required to prevent output transistor damage.
This level of protection enables Crown to increase out-put efficiency to
never-before-achieved levels while greatly increasing amplifier reliability.
The on-board intelligence is monitored two ways. First, the amplifier’s ODEP
indicators show whether the unit is functioning correctly or if ODEP is
limiting output. Second, ODEP data is fed to the amplifier’s internal P.I.P.
connector so advanced P.I.P. modules like the IQ-P.I.P. can use it to monitor
and control the amplifier. This is how ODEP keeps the show going with maximum
power and maximum protection at all times.
Standby Mode
An important part of a Studio Reference amplifier’s protection systems is
standby mode. Standby protects the amplifier during potentially catastrophic
conditions. It temporarily removes power from the high-voltage supplies to
protect the amplifier and its loads. Standby mode can be identified using the
table in Figure 4.2. Standby mode is activated in five situations. First, when
you turn on the enable switch, standby mode is activated to provide turn-on
protection. This power-up de-lay lets other system components settle before
any signals are amplified and it provides some power-up “randomness” for
multiple units so the system’s start-up current demands are better distributed
over time. The amplifier’s overvoltage protection circuitry will put both
channels into standby when excessive AC mains voltage is detected. Studio
Reference amplifiers should not be operated with an AC mains voltage of more
than 10% over the unit’s rated voltage.
If dangerous subsonic frequencies or direct current (DC) is detected in the
amplifier’s output, the unit will activate its DC / low-frequency protection
circuitry and put the affected channels in standby. This protects the loads
and prevents oscillations. The amplifier resumes normal operation as soon as
it no longer detects dangerous low-frequency or DC output. Although it is
extremely unlikely that you will ever activate the amplifier’s DC / low-
frequency protection system, proper source materials such as subsonic square
waves or input overloads that result in excessively clipped signals can
activate this system.
The amplifier’s fault protection system will put an amplifier channel into
standby mode in rare situations where heavy common-mode current is detected in
the channel’s output. The amplifier should never output heavy common-mode
current unless its circuitry is damaged in some way, and putting the channel
into standby mode helps to prevent further damage.
The amplifier’s transformer thermal protection circuit is activated in very
unusual circumstances where the unit’s transformer temperature rises to unsafe
levels. Under these abnormal conditions, the amplifier will put both channels
into standby mode. The amplifier will return to normal operation after the
transformer cools to a safe temperature. (For more information on trans-former
thermal protection, refer to the section that follows.)
Transformer Thermal Protection
All Studio Reference amplifiers have transformer thermal protection which
protects the power supplies from damage under rare conditions where the
transformer temperature rises too high. A thermal switch embedded in the
transformer removes power to the high-voltage power supplies if it detects
excessive heat. The switch automatically resets itself as soon as the
transformer cools to a safe temperature.
If your amplifier is operated within rated conditions, it is extremely
unlikely that you will ever see it activate transformer thermal protection.
One reason is that ODEP keeps the amplifier working under very severe
conditions. Even so, higher-than-rated output levels, excessively low-
impedance loads and unreasonably high input signals can generate more heat in
the transformer than in the output devices. This can overheat the transformer
and activate its protection system.
Studio Reference amplifiers are designed to keep working under conditions
where other amplifiers would fail. But even when the limits of a Studio
Reference amplifier are exceeded, it still protects itself—and your
investment—from damage.
Circuit Breaker
A back panel circuit breaker is provided to prevent excessive current draw by
the high-voltage power supplies. A Studio Reference / configured for 100 to
120 VAC has a 30 amp circuit breaker, while the 220 to 240 VAC version has a
20 amp circuit breaker. A Studio Reference // configured for 100 to 120 VAC
uses a 20 amp circuit breaker, and the 220 to 240 VAC version has a 10 amp
circuit breaker. With rated loads and output levels, this breaker should only
trip in the incredibly rare instance of a catastrophic amplifier failure. The
ODEP system keeps the amplifier safe and operational under most other severe
conditions. The breaker can also trip in situations where extremely low-
impedance loads and high output levels result in current draw that exceeds the
breaker’s rating. Again, this should only be possible when operating outside
rated conditions, like when the amplifier is used to drive a 1 ohm load, or
when an input signal is clipped severely.
Controls
- Turn down the level of your audio source. For example, set your mixer’s volume to –/ (off).
- Turn down the amplifier’s level controls.
- Turn on the enable switch. The enable indicator be-side the switch should glow. During the four-second turn-on delay that immediately follows, the indicators will flash as described in Figure 4.2. After the delay, the ODEP indicators should come on with full brilliance and the IOC and signal presence indicators should function normally.
- After the turn-on delay, turn up your source to the maximum desired level.
- Turn up the amplifier’s level controls until the maximum desired sound level is achieved.
- Turn down the level of your audio source to its normal range.The front panel enable switch is used to turn the amplifier on and off. If you ever need to make any wiring or installation changes, don’t forget to disconnect the power cord first. Please follow these steps when first turning on your amplifier:
Each of the front panel level controls has 31 detents for accurately repeatable settings. In the Bridge-Mono and Parallel-Mono modes, the channel 2 level control should be turned down. The meter switches are located behind the front panel. They make it possible to switch between the dynamic range and signal level display modes for the meters, or you can turn the meters off. From the factory, the meters automatically display dynamic range (which is computed as the ratio of peak to average out-put power). To change these switches, you will need to remove part of the front panel. A phillips screwdriver will be needed, and it will help to remove the amplifier if it is mounted in a rack. Follow these steps:
- Make sure the amplifier is turned off and its power cord is disconnected from the AC mains source.
- Remove the two screws that hold each end cap in place and remove both end caps (see Figure 3.2).
- Remove the six screws that hold each handle in place and remove each handle (see Figure 4.3).
- Remove the dust filter by gently pulling it away from the front panel.
- Remove the two screws that secure the lower half of the front panel and remove the lower front panel.
- Locate the meter switches as shown in Figure 4.4. Set the switches as desired. The left switch is used to turn the meters on and off, and the right switch is used to change display modes.
- Reassemble the front panel, handles and end caps in reverse order of disassembly.
- Install the amplifier and reconnect power.
The input sensitivity switch is located inside the amplifier’s P.I.P. compartment. It is factory-set to a fixed voltage gain of 26 dB. For standard 1 kHz power into 8 ohms, this is equivalent to an input sensitivity of 4.0 volts for the Studio Reference / and 2.7 volts for the Studio Reference //. If needed, it can be switched to a sensitivity of 0.775 or 1.4 volts. Here is the procedure:
- Turn off the amplifier and disconnect the power cord from the receptacle.
- Remove the P.I.P. module.
- Locate the access hole for the sensitivity switch inside the chassis opening (see Figure 4.5).
- Set the switch to the desired position noted on the access hole label.
- Replace the P.I.P. module and restore power.
The ground lift switch located on the back panel can provide isolation between
the phone jack input grounds and the AC (chassis) ground. It does not affect
the P.I.P. module’s input connectors. Slide the switch to the left to isolate
or “lift” the grounds.
Note: The noninverted and inverted signal lines for the P.I.P. module are
connected in parallel with the corresponding lines of the phone jack inputs.
The input signal grounds are not paralleled. Specifically, XLR pins 2 and 3
are connected in parallel with the tip and ring of the corresponding phone
jack. However, pin 1 of the XLR is not connected in parallel with the sleeve
of the phone jack. This makes it possible for a P.I.P. module to handle its
own signal grounds independently.
The amplifier’s circuit breaker protects the power supplies from overload. The
breaker’s reset switch is located on the back panel. Facing the back panel,
move the reset switch the left to disconnect power to the power supplies, or
to the right to reconnect power. If the circuit breaker trips, the front panel
enable indicator will turn off. If this occurs, turn off the enable switch,
flip the reset switch to the right (on), and then turn the enable switch back
on. If it trips again or the amplifier does not operate properly, contact an
authorized service center or Crown’s Technical Support Group.
Filter Cleaning
A dust filter is provided on the amplifier’s air intake (see Figure 2.1). If
this filter becomes clogged, the unit will not cool as efficiently as it
should and high heat sink temperatures may produce lower-than-normal output.
To clean the filter, gently pull it away from the front panel and wash it with
mild dishwashing detergent and warm water. Be sure the filter is dry before
you reinstall it. Replacement filters may be ordered from the factory. Dust
filters are not 100% efficient—long term this may require heat sink cleaning
by a qualified technician. Internal cleaning information is available from our
Technical Support Group.
Technical Information
Overview
Studio Reference amplifiers incorporate several new technological advancements
including real-time computer simulation of output transistor stress, low-
stress output stages, an advanced heat sink embodiment and the Programmable
Input Processor (P.I.P.) expansion system.
Custom circuitry is incorporated to limit temperature and current to safe
levels making it highly reliable and tolerant of faults. Unlike many lesser
amplifiers, it can operate at its voltage and current limits without self-de-
structing.
Studio Reference amplifiers are protected against all common hazards that
plague high-power amplifiers including shorted, open or mismatched loads;
over-loaded power supplies, excessive temperature, chain-destruction
phenomena, input overload and high-frequency blowups. The unit protects
loudspeakers from input and output DC, as well as turn-on and turn-off
transients.
Real-time computer simulation is used to create an analogue of the junction
temperature of the output transistors (hereafter referred to as the output
devices). Current is limited only when the device temperature becomes
excessive—and only by the minimum amount necessary. This patented approach
maximizes the available output power and eliminates overheating—the major
cause of device failure.
Crown also invented the four-quadrant topology used in the output stages of
each Studio Reference amplifier (see Figure 5.1). This special circuitry is
called the grounded bridge. It makes full use of the power supply by
delivering peak-to-peak voltages to the load that are twice the voltage seen
by the output devices.
As its name suggests, the grounded bridge topology is referenced to ground. Composite devices are constructed to function as gigantic NPN and PNP devices to handle currents that exceed the limits of available devices. Each output stage has two composite NPN and two composite PNP devices.
The devices connected to the load are referred to as “high-side NPN and PNP”
and the devices connected to ground are referred to as “low-side NPN and PNP.”
Positive current is delivered to the load by increasing conductance
simultaneously in the high-side NPN and low-side PNP stage, while
synchronously decreasing conductance of the high-side PNP and low-side NPN.
The two channels may be used together to double the voltage (Bridge-Mono) or
the current (Parallel-Mono) presented to the load. This feature gives you the
flexibility to maximize power available to the load.
A wide bandwidth, multiloop design is used for state-of-the-art compensation.
This produces ideal behavior and results in ultra-low distortion values.
Aluminum extrusions are used widely for heat sinks in power amplifiers due to
their low cost and reasonable performance. However, measured on watts per
pound or watts per volume basis, the extrusion technology doesn’t perform
nearly as well as the heat sink technology developed for Studio Reference
amplifiers.
Our heat sinks are fabricated from custom convoluted fin stock that provides
an extremely high ratio of area to volume, or area to weight. All power
devices are mounted directly to the heat sinks which are also electrically at
the Vcc potential. Electrifying the heat sinks improves thermal performance by
eliminating the insulating interface underneath the power devices. The chassis
itself is even used as part of the thermal circuit to maximize utilization of
the available cooling resources.
Circuit Theory
Power is provided by low-field toroidal power trans-former T1. The secondaries
of T1 are full-wave rectified (by D1 through D4, D22 and D24) and filtered by
large computer-grade capacitors. A thermal switch embedded in the transformer
protects it from overheating. Monolithic regulators provide a regulated ±15
volts.
Stereo Operation
For simplicity, the discussion of Stereo operation will refer to only one
channel. Mono operation will be discussed later. Please refer to the block
diagram in Fig-ure 5.1 and the schematics included with this manual. The input
signal at the phone jack passes directly into the balanced gain stage
(U104-A). When a P.I.P. model is used, the input signal first passes through
the P.I.P.’s circuitry and then to the balanced gain stage. The balanced gain
stage (U104-A) causes balanced to single-ended conversion using a difference
amplifier. From there, gain can be controlled with the front panel level
controls and the input sensitivity switch. The error amp (U104-C) amplifies
the difference between the output signal and the input signal from the gain
pot, and drives the voltage-translator stage.
From the error amp, the voltage translator stage channels the signal to the
Last Voltage Amplifiers (LVAs) depending on the signal polarity. The +LVA
(Q104 and Q105) and the –LVA (Q110 and Q111) drive the fully complementary
output stage with their push-pull effect through the bias servo Q318. The bias
servo Q318 is thermally coupled to the heat sink, and sets the quiescent bias
current in the output stage to lower the distortion in the crossover region of
the output signal. With the voltage swing provided by the LVAs, the signal
then gains current amplification through the triple Darlington emitter-
follower output stage. The bridge-balanced circuit (U104-D) receives a sig-nal
from the output of the amplifier, and differences it with the signal at the
Vcc supply. The bridge-balanced circuit then develops a voltage to drive the
bridge-balanced output stage. This results in the Vcc supply having exactly
one-half of the output voltage added to its quiescent voltage. Bias servo Q300
sets the quiescent current point for the bridge-balanced output stage.
The protection mechanisms that affect the signal path are implemented to
protect the amplifier under real-world conditions. These conditions are high
instantaneous current, excessive temperature, and output device operation
outside safe conditions.
Q107 and Q108 act as a conventional current limiter, sensing current in the
output stage. When output current at any instant exceeds the design criteria,
the limit-ers remove drive from the LVAs, thus limiting current in the output
stage to a safe level.
To further protect the output stages, the patented ODEP circuitry is used. It
produces an analog output proportional to the always-changing safe operating
area of the output transistors. This output controls the translator stage
previously mentioned, removing any further drive that may exceed the safe
operating area of the output stage. Thermal sensor S100 gives the ODEP circuit
vital information on the operating temperature of the heat sink on which the
output devices are mounted. Should the amplifier fail in such a way that would
cause DC across the output leads, the DC/low-frequency protection circuit
senses this on the negative feedback loop and shuts down the power supply
until the DC is removed.
Bridge-Mono Operation
By setting the back panel stereo/mono switch to Bridge-Mono, the user can
convert the amplifier into a bridged, single-channel amplifier. With a signal
applied to the channel 1 input jack and the load connected across the two
channels’ red (+) 5-way binding posts, twice the voltage can be output.
The channel 1 output feeds the channel 2 error amp U204-C. Because there is a
net inversion, channel 2 output is out of polarity with channel 1. This
produces twice as much voltage across the load. Each channel’s protection
mechanisms work independently if a fault occurs.
Parallel-Mono Operation
With the stereo/mono switch set to Parallel-Mono, the output of channel 2 is
paralleled with the output of channel 1. A suitable jumper capable of handling
high current must be connected across the red (+) 5-way posts to gain the
benefits of this mode of operation.
The signal path for channel 1 is the same as previously discussed, except
channel 1 also drives the output stage of channel 2. The channel 2 balanced
input, error amp, translators and LVAs are disconnected and no longer control
the channel 2 output stage. Disconnecting the front-end stages from the
channel 2 output causes the channel 2 IOC circuit to note that the input
waveform (which is not present) does not match the output waveform (which is
driven by the channel 1 input signal). This activates the channel 2 IOC
indicator any time the amplifier is switched into Parallel-Mono mode. The
channel 2 output stage and protection mechanisms are also coupled through S1
and function as one. In Parallel-Mono mode, twice the current of one channel
alone can be obtained. Because the channel 2 ODEP circuit is coupled through
S1, this gives added protection if a fault occurs in the channel 2 output
stage. The ODEP circuit of channel 2 will limit the output of both output
stages by removing the drive from the channel 1 translator stages.
Specifications
The following applies to units in Stereo mode with 8 ohm loads and an input sensitivity of 26 dB gain unless otherwise specified.
- Low-Distortion 1 kHz Power: refers to maximum average power in watts at 1 kHz with 0.02% THD and noise.
- Standard 1 kHz Power: refers to maximum average power in watts at 1 kHz with 0.1% THD and noise.
- Full Bandwidth Power: refers to the maximum average power in watts from 20 Hz to 20 kHz with 0.1% THD and noise.
Performance
- Frequency Response: ±0.1 dB 20 Hz to 20 kHz at 1 watt (see Figure 6.5).
- Phase Response: +5 to –15 degrees from 20 Hz to 20 kHz at 1 watt (see Figure 6.8).
- Signal-to-Noise: (A-weighted)
- Studio Reference /: Greater than 120 dB below rated full bandwidth power.
- Studio Reference //: Greater than 117 dB below rated full bandwidth power.
- Total Harmonic Distortion (THD): Less than 0.02% at rated low-distortion 1 kHz power. Less than 0.1% at rated full bandwidth power.
- Intermodulation Distortion (IMD): (60 Hz and 7 kHz 4:1)
- Studio Reference /: Less than 0.005% from full bandwidth power to 78 watts rising linearly to 0.025% at 78 milliwatts.
- Studio Reference //: Less than 0.005% from full bandwidth power to 36 watts rising linearly to 0.025% at 36 milliwatts.
- Damping Factor: Greater than 20,000 from 10 Hz to 200 Hz, and greater than 2,500 at 1 kHz (see Figure 6.6).
- Crosstalk: /(At rated full bandwidth power)
- Studio Reference /: Better than 100 dB from 20 Hz to 100 Hz falling linearly to better than 70 dB at 20 kHz (see Figure 6.10).
- Studio Reference //: Better than 100 dB from 20 Hz to 100 Hz falling linearly to better than 65 dB at 20 kHz (see Figure 6.10).
- Common Mode Rejection (CMR): (At rated full bandwidth power) See Figure 6.9.
- Voltage Gain: (With level controls set for maximum output) At the 26 dB gain setting, 20:1 ±3% or 26 dB ±0.25 dB.
- Studio Reference /: At 0.775 volt sensitivity, 103:1±12% or 40 dB ±1 dB; at 1.4 volt sensitivity 57:1 ±12%or 35 dB ±1 dB.
- Studio Reference /: At 0.775 volt sensitivity, 69:1±12% or 37 dB ±1 dB; at 1.4 volt sensitivity 38:1 ±12%or 32 dB ±1 dB.
Power
-
Power Bandwidth: (At standard 1 kHz power)
- Studio Reference / : –1 dB from 5 Hz to 27.5 kHz and – 3 dB from 3 Hz to 32.8 kHz.
- Studio Reference //: –1 dB from 5 Hz to 28.6 kHz and – 3 dB from 2.3 Hz to 34.4 kHz.
-
Output Power: The following are guaranteed minimums for low-distortion 1 kHz power from units configured for 120 VAC, 60 Hz power. For more information on power specifications, see the matrices that follow.
-
Studio Reference /
-
Stereo mode (with both channels driven):
1,160 watts into 4 ohms.
780 watts into 8 ohms. -
Bridge-Mono mode:
2,220 watts into 8 ohms.
1,580 watts into 16 ohms. -
Parallel-Mono mode:
2,315 watts into 2 ohms.
1,565 watts into 4 ohms. -
Studio Reference //
-
Stereo mode (with both channels driven):
555 watts into 4 ohms.
355 watts into 8 ohms. -
Bridge-Mono mode:
1,110 watts into 8 ohms.
715 watts into 16 ohms. -
Parallel-Mono mode:
1,115 watts into 2 ohms.
710 watts into 4 ohms.
-
-
Load Impedance: Safe with all types of loads. Rated for 4 to 8 ohms in Stereo mode, 8 to 16 ohms in Bridge-Mono mode, and 2 to 4 ohms in Parallel-Mono mode.
-
Required AC Mains: 50 or 60 Hz; 100, 120, 200, 220 or 240 VAC (±10%). Both units draw 90 watts or less at idle. See Section 7 for detailed information on AC power draw, current draw and thermal dissipation.
It is extremely important to have adequate AC power for the amplifier. Power amplifiers cannot create energy—they must have the required voltage and current to deliver the undistorted rated power you expect.
Controls
- Enable: A front panel push button used to turn the amplifier on and off.
- Level: A front panel rotary potentiometer for each channel with 31 detents used to control the output level.
- Stereo/Mono: A three-position back panel switch used to select Stereo, Bridge-Mono and Parallel-Mono mode.
- Sensitivity: A three-position switch inside the P.I.P. compartment used to select the input sensitivity for both channels: 0.775 or 1.4 volts for standard 1 kHz power, or a 26 dB voltage gain.
- Meter On/Off: A two-position switch behind the front panel used to turn the front panel meters on or off.
- Meter Display Mode: A two-position switch behind the front panel used to set the display mode for the front panel meters. Display modes include dynamic range of the output signal in dB or output levels in dB.
- Ground Lift: A two-position back panel switch used to isolate the input phone jack and AC (chassis) grounds.
- Reset: A two-position back panel switch used to reset the AC mains circuit breaker.
Indicators
- Enable: This indicator shows the on/off status of the unit’s low-voltage power supply.
- Signal: Each channel has a signal indicator that flashes to show audio output.
- IOC: Each channel has an IOC indicator that flashes if the output waveform differs from the input waveform by 0.05% or more. The LEDs act as sensitive distortion indicators to provide proof of distortion-free performance. In Parallel-Mono mode the channel 2 IOC light stays on.
- ODEP: Each channel has an ODEP indicator that shows the channel’s reserve energy status. Normally, the LEDs are brightly lit to show that reserve energy is available. In the rare event that a channel has no reserve, its indicator will dim in proportion to ODEP limiting. An ODEP indicator may also turn off under other more unusual circumstances (see Section 4.3).
- Dynamic Range/Level Meter: Each channel has a five-segment meter that displays either the dynamic range of the output signal in dB or the output level in dB. (From the factory, the amplifier is set to display dynamic range.) As dynamic range meters, they show the ratio of the peak to average power of each channel. As output level meters they show how high the output levels are relative to standard 1 kHz power.
Input/Output
- Input Connector: Two balanced phone jacks on the back panel and two balanced three-pin XLR connectors on the factory-installed P.I.P.-FX (see Section 8 for information on optional P.I.P. modules).
- Input Impedance: Nominally 10 K ohms, balanced. Nominally 5 K ohms, unbalanced.
- Input Sensitivity: Settings include 0.775 volts or 1.4 volts for standard 1 kHz power, or a 26 dB voltage gain (see Section 4.4 for more information).
- Output Connectors: Two sets of color-coded 5-way binding posts for each channel (for connecting banana plugs, spade lugs or bare wire).
- Output Impedance: Less than 10 milliohms in series with 2.5 microhenries.
- DC Output Offset: (Shorted input) ±2 millivolts.
Output Signal
- Stereo: Unbalanced, two-channel.
- Bridge-Mono: Balanced, single-channel. Channel 1 controls are active; channel 2 should be turned down.
- Parallel-Mono: Unbalanced, single-channel. Channel 1 controls are active; channel 2 is bypassed.
Protection
If unreasonable operating conditions occur, the protection circuitry limits
the drive level to protect the output stages especially in the case of
elevated temperature. Transformer overheating will result in a temporary
shutdown. Controlled slew-rate voltage amplifiers protect the unit against RF
burnouts. Input overload protection is furnished at the amplifier input to
limit current.
- Turn On: The four-second turn-on delay prevents dangerous turn-on transients. To change the turn-on delay time, contact Crown’s Technical Support Group.
Construction
- Steel chassis with durable black finish, aluminum front panel with super-gloss Imron® finish, Lexan overlay, and a specially designed flow-through ventilation system from front to side panels.
- Cooling: Convection cooling with assistance from the computerized, on-demand proportional cooling fan.
- Dimensions: Standard 19 inch (48.3 cm) rack mount width (EIA RS-310-B), 7 inch (17.8 cm) height, 16 inch (40.6 cm) depth behind mounting surface and 2.75 inch (7 cm) protrusion in front of mounting surface.
- Approximate Weight: Center of gravity is about 6 inches (15.2 cm) behind the front mounting surface.
- Studio Reference /: 60 pounds, 11 ounces (27.6 kg) net; 74 pounds, 3 ounces (33.7 kg) shipping weight.
Studio Reference //: 56 pounds, 2 ounces (25.5 kg) net; 69 pounds, 10 ounces (31.6 kg) shipping weight.
- Studio Reference /: 60 pounds, 11 ounces (27.6 kg) net; 74 pounds, 3 ounces (33.7 kg) shipping weight.
Crown specifications are guaranteed for three years.
In an effort to provide you with as much information as possible about the
high power-producing capabilities of your amplifier, we have created the
following power matrices.
Minimum Guaranteed Power Specifications
Crown’s minimum power specifications represent the absolute smallest amount of
output power you can expect from your amplifier when it is driven to full
output under the given conditions. Some spaces in each matrix may be left
blank because the same guarantee is not provided for those conditions—however,
your amplifier will perform well under all conditions listed in each matrix.
When measuring power, 0.1% THD appears to be the industry standard for
distortion. Two of the maximum average power specifications shown in each
minimum power matrix are measured at 0.1% THD so you can easily compare Crown
specifications to those of other manufacturers. But this high level of
distortion actually allows for some clipping which is undesirable. Because of
this, a maximum average power specification at 0.05% THD is included in each
minimum power matrix which represents non-clipped conditions. Also, power at
0.02% THD is provided in the preceding specifications. Although most
manufacturers do not give power specifications at 0.05% or 0.02% THD, we
encourage them to provide these specifications so you will have a more
realistic representation of the way amplifiers should be used in the real
world—without a clipped output signal. Many manufacturers publish power specs
with a tolerance of ±1 dB or worse. This means their amplifier can deviate
more than 20% in output! A 100 watt amplifier would meet their specification
if it only produced 79.4 watts. Other manufacturers qualify their specs by
saying they are “typical,” “subject to manufacturing tolerances,” “single
channel driven” or that they are specified with “fuses bypassed.” Each of
these statements effectively removes any performance guarantee. In fact, some
manufacturers use these tactics to generate large power numbers, and they
don’t even print a disclaimer. We take a different approach at
Crown—our amplifiers are guaranteed to meet or exceed their specifications for
three years. Further, because our published specs are set below our “in-house”
measurements, you can expect every Crown amplifier to exceed its published
minimum power specs. We believe you should get what you pay for.
Minimum Power Notes:
Studio Reference I – Minimum Guaranteed Power (Watts)
AC Mains| Stereo/Mono Mode| Load (Ohms)| Maximum Average| FTC Continuous Average
0.1% THD + Noise (See note 4)
0.1% THD+N
(See note 1)
| 0.1% THD+N
(See note 2)
| 0.05% THD+N
(See note 3)
1 kHz| 20Hz-20kHz| 1 kHz| 1 kHz| 20Hz-20kHz
120 VAC, 60 Hz| Stereo (both channels driven)| 4| 1,190| 1,075|
1,170| |
8| 800| 760| 790| 785| 750
Bridge- Mono (balanced output)| 8| 2,375| 2,150| 2,335| |
16| 1,595| 1,535| 1,580| 1,575| 1,490
Parallel- Mono| 2| 2,350| | 2,320| |
4| 1,580| | 1,565| 1,565|
100 VAC, 50 Hz| Stereo (both channels driven)| 4| 1,095| 970| 1,075|
|
8| 750| 725| 745| 750| 715
Bridge- Mono (balanced output)| 8| 2,200| 1,985| 2,160| |
16| 1,515| 1,440| 1,495| 1,515| 1,440
Parallel- Mono| 2| 2,185| | 2,175| |
4| 1,500| | 1,480| 1,490|
240 VAC, 50 Hz| Stereo (both channels driven)| 4| 1,255| 1,135|
1,255| |
8| 825| 820| 815| 820| 795
Bridge- Mono (balanced output)| 8| 2,505| 2,280| 2,460| |
16| 1,660| 1,610| 1,645| 1,660| 1,595
Parallel- Mono| 2| 2,485| | 2,475| |
4| 1,655| | 1,640| 1,640|
All minimum power specifications are based on 0.5% regulated AC mains with THD of less than 1.0% and an ambient room temperature of 70° F (21° C). Standard EIA power (RS-490) is not shown here because it is identical to FTC Continuous Average Power.
- A 1 kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until THD reaches 0.1%. At this point, average power per channel is reported.
- A sine wave is presented to the amplifier over the range from 20 Hz to 20 kHz and the output monitored for nonlinear distortion. The level at each frequency is increased until THD reaches 0.1%. At this point, average power per channel is reported.
- A 1 kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until THD reaches 0.05%. At this point, average power per channel is reported.
- Continuous power in the context of Federal Trade Commission testing is understood to be a minimum of five minutes of operation. Harmonic distortion is measured as the RMS sum total and given as a percentage of the fundamental output voltage. This applies for all wattages greater than 0.25 watts.
Studio Reference II – Minimum Guaranteed Power (Watts)
AC Mains| Stereo/Mono Mode| Load (Ohms)| Maximum Average| FTC Continuous Average
0.1% THD + Noise (See note 4)
0.1% THD+N
(See note 1)
| 0.1% THD+N
(See note 2)
| 0.05% THD+N
(See note 3)
1 kHz| 20Hz-20kHz| 1 kHz| 1 kHz| 20Hz-20kHz
120 VAC, 60 Hz| Stereo
(both channels driven)
| 4| 565| 495| 560| 555| 470
8| 360| 340| 355| 360| 340
Bridge- Mono
(balanced output)
| 8| 1,145| 1,020| 1,130| 1,105| 960
16| 720| 690| 715| 720| 680
Parallel- Mono| 2| 1,135| | 1,125| 1,105|
4| 715| | 715| 715|
100 VAC, 50 Hz| Stereo
(both channels driven)
| 4| 535| 460| 525| 520| 440
8| 355| 330| 340| 345| 320
Bridge- Mono
(balanced output)
| 8| 1,080| 970| 1,070| 1,045| 900
16| 700| 665| 695| 690| 655
Parallel- Mono| 2| 1,065| | 1,055| 1,030|
4| 690| | 685| 675|
240 VAC, 50 Hz| Stereo
(both channels driven)
| 4| 595| 520| 585| 580| 465
8| 375| 360| 370| 375| 355
Bridge- Mono
(balanced output)
| 8| 1,205| 1,060| 1,195| 1,145| 915
16| 755| 720| 750| 740| 700
Parallel- Mono| 2| 1,190| | 1,175| 1,155|
4| 755| | 745| 735|
Maximum Power Specifications
Crown’s maximum power specifications represent the largest amount of output
power you can expect from your amplifier when it is driven to full output
under the given conditions. These specifications can be used to prevent
loudspeakers and hearing damage.
The maximum power matrices include specifications for single cycle and 40
millisecond burst sine waves. Burst signals act like large transient peaks
that are present in common source signals. Loudspeakers can respond to a
single-cycle burst, so the single-cycle burst specifications should be used to
help you protect your loudspeakers. In contrast, a 40-millisecond burst
represents the typical response time of the human ear. Your ear will not
respond to the entire dynamic change of a burst that lasts less than 40
milliseconds. The burst power specifications are provided at 0.05% THD which
is a practical low distortion condition. Operating the amplifier at levels
higher than 0.05% THD can result in output power levels that are higher than
those listed in the maximum power matrices.
Studio Reference I – Maximum Power (Watts)
AC Mains| Stereo/Mono Mode| Load (Ohms)| Single Cycle Tone Burst
0.05% Distortion + Noise (See note 1)
| 40 Millisecond Tone Burst
0.05% Distortion + Noise (See note 2)
50 Hz| 1 kHz| 7 kHz| 50 Hz| 1 kHz| 7 kHz
120 VAC, 6 0 Hz| Stereo (both channels driven)| 4|
1,435| 2,180| 2,030| 1,295| 1,220| 1,220
8| 900| 1,165| 1,120| 835| 820| 830
Bridge- Mono (balanced output)| 8| 2,855| 4,355| 4,080| 2,635| 2,425|
2,400
16| 1,780| 2,345| 2,215| 1,695| 1,635| 1,650
Parallel- Mono| 2| 2,820| 4,380| 4,075| 2,605| 2,420| 2,395
4| 1,795| 2,340| 2,230| 1,700| 1,620| 1,650
100 VAC, 50 Hz| Stereo (both channels driven)| 4| 1,380|
2,150| 2,015| 1,260| 1,135| 1,135
8| 900| 1,155| 1,100| 820| 780| 790
Bridge- Mono (balanced output)| 8| 2,780| 4,285| 4,020| 2,595| 2,260|
2,235
16| 1,740| 2,320| 2,195| 1,600| 1,555| 1,570
Parallel- Mono| 2| 2,780| 4,325| 3,985| 2,455| 2,250| 2,250
4| 1,780| 2,320| 2,190| 1,620| 1,545| 1,575
240 VAC, 50 Hz| Stereo (both channels driven)| 4| 1,470|
2,220| 2,065| 1,370| 1,290| 1,275
8| 930| 1,190| 1,135| 880| 850| 860
Bridge- Mono (balanced output)| 8| 2,945| 4,360| 4,090| 2,695| 2,560|
2,505
16| 1,830| 2,360| 2,250| 1,750| 1,685| 1,705
Parallel- Mono| 2| 2,970| 4,415| 4,100| 2,715| 2,525| 2,550
4| 1,810| 2,355| 2,240| 1,745| 1,685| 1,700
Maximum Power Notes:
All maximum power specifications are based on 0.5% regulated AC mains with THD
of less than 1.0% and an ambient room temperature of 70° F (21° C). Although
it is an unusual condition, your amplifier can function well with AC mains
voltages up to 10% over the specified line voltage. With overvoltage
conditions, your amplifier may be capable of delivering instantaneous power
levels up to 20% greater than the specifications in the matrix.
- A single-cycle sine wave is presented to the amplifier and monitored for nonlinear distortion. The average power during the burst is reported. Loudspeakers must be able to withstand this level if they are to be safely used with this amplifier.
- A 40-millisecond sine wave burst (10 percent duty cycle) is presented to the amplifier and monitored for nonlinear distortion. Average power during the burst is reported. This power level is a measurement of the amplifier’s maximum transient power that can be perceived by the human ear.
Studio Reference II – Maximum Power (Watts)
AC Mains| Stereo/Mono Mode| Load (Ohms)| Single Cycle Tone Burst
0.05% Distortion + Noise (See note 1)
| 40 Millisecond Tone Burst
0.05% Distortion + Noise (See note 2)
50 Hz| 1 kHz| 7 kHz| 50 Hz| 1 kHz| 7 kHz
120 VAC, 6 0 Hz| Stereo (both channels driven)| 4|
630| 875| 820| 605| 580| 585
8| 395| 480| 455| 375| 370| 375
Bridge- Mono (balanced output)| 8| 1,345| 1,785| 1,685| 1,245| 1,185|
1,185
16| 800| 970| 935| 750| 755| 770
Parallel- Mono| 2| 1,330| 1,770| 1,670| 1,205| 1,170| 1,170
4| 790| 965| 920| 755| 745| 765
100 VAC, 50 Hz| Stereo (both channels driven)| 4| 690|
905| 855| 650| 610| 610
8| 405| 495| 470| 385| 385| 395
Bridge- Mono (balanced output)| 8| 1,395| 1,840| 1,750| 1,315| 1,230|
1,240
16| 830| 1,005| 965| 785| 780| 800
Parallel- Mono| 2| 1,405| 1,830| 1,730| 1,330| 1,220| 1,220
4| 815| 995| 955| 785| 770| 790
240 VAC, 50 Hz| Stereo (both channels driven)| 4| 650|
880| 830| 595| 565| 565
8| 365| 450| 430| 345| 340| 350
Bridge- Mono (balanced output)| 8| 1,305| 1,775| 1,715| 1,195| 1,130|
1,150
16| 790| 965| 940| 735| 735| 755
Parallel- Mono| 2| 1,295| 1,765| 1,655| 1,185| 1,120| 1,130
4| 785| 965| 920| 750| 725| 745
AC Power Draw and Thermal Dissipation
This section provides detailed information about the amount of power and current drawn from the AC mains by Studio Reference amplifiers and the amount of heat produced under various conditions. The calculations presented here are intended to provide a very realistic and reliable depiction of the amplifiers. The following assumptions were made:
- The amplifier’s available channels are loaded, and full, standard 1 kHz power is being delivered.
- Amplifier efficiency at standard 1 kHz power is estimated to be 65%.
- Quiescent power draw is 90 watts (an almost negligible amount for full-power calculations).
- Quiescent thermal dissipation equals 307 btu/hr at 90 watts.
- Duty cycle takes into account the typical crest factor for a particular type of source material.
- Duty cycle of pink noise is 50%.
- Duty cycle of highly compressed rock ‘n’ roll midrange is 40%.
- Duty cycle of uncompressed rock ‘n’ roll is 30%.
- Duty cycle of background music is 20%.
- Duty cycle of continuous speech is 10%.
- Duty cycle of infrequent paging is 1%.
Here are the equations used to calculate the data presented in Figures 7.1 and 7.2:
The estimated quiescent power draw of 90 watts is a maximum figure, and assumes the fan is running at high speed. The following equation converts power draw in watts to current draw in amperes:
The power factor constant of 0.83 is needed to compensate for the difference in phase between in the AC mains voltage and current. The following equation was used to calculate thermal dissipation:
The constant 0.35 is inefficiency (1.00 – 0.65) and the factor 3.415 converts watts to btu/hr. Thermal dissipation in btu is divided by the constant 3.968 to get kcal. If you plan to measure output power under real-world conditions, the following equation may be helpful:
Studio Reference I
| L O A D
---|---
8 Ohm Stereo / 16 Ohm Bridge-Mono / 4 Ohm Parallel-Mono| 4 Ohm Stereo / 8 Ohm
Bridge-Mono / 2 Ohm Parallel-Mono
Duty Cycle| AC Mains Power Draw (Watts)| Current Draw (Amps)| Thermal
Dissipation| AC Mains Power Draw (Watts)| Current Draw (Amps)| Thermal
Dissipation
100-120 V| 220-240 V| btu/hr| kcal/hr| 100-120 V| 220-240 V| btu/hr| kcal/hr
50%| 1325| 15.9| 7.2| 1,780| 450| 1,925| 23.1| 10.5| 2,500| 630
40%| 1075| 12.9| 5.9| 1,485| 375| 1,555| 18.7| 8.5| 2,060| 520
30%| 830| 10.0| 4.5| 1,190| 300| 1,190| 14.3| 6.5| 1,620| 410
20%| 585| 7.0| 3.2| 900| 230| 825| 9.9| 4.5| 1,185| 300
10%| 340| 4.1| 1.8| 605| 155| 460| 5.5| 2.5| 745| 190
Studio Reference II
L O A D | |
---|---|
8 Ohm Stereo / 16 Ohm Bridge-Mono / 4 Ohm Parallel-Mono | 4 Ohm Stereo / 8 Ohm |
Bridge-Mono / 2 Ohm Parallel-Mono
Duty Cycle| AC Mains Power Draw (Watts)| Current Draw (Amps)| Thermal
Dissipation| AC Mains Power Draw (Watts)| Current Draw (Amps)| Thermal
Dissipation
100-120 V| 220-240 V| btu/hr| kcal/hr| 100-120 V| 220-240 V| btu/hr| kcal/hr
50%| 645| 7.8| 3.5| 970| 245| 975| 11.7| 5.3| 1,360| 345
40%| 535| 6.4| 2.9| 840| 215| 795| 9.6| 4.4| 1,150| 290
30%| 425| 5.1| 2.3| 705| 180| 620| 7.5| 3.4| 940| 240
20%| 315| 3.8| 1.7| 575| 145| 445| 5.3| 2.4| 730| 185
10%| 205| 2.4| 1.1| 440| 115| 270| 3.2| 1.5| 520| 135
Accessories
P.I.P. Modules
One advantage of Studio Reference amplifiers is the ability to customize them
using P.I.P. (Programmable In-put Processor) modules. Each amplifier is
equipped with an edge card connector inside the back panel P.I.P. compartment.
The modules install easily:
WARNING: Disconnect power to the amplifier when installing or removing a
P.I.P. module.
Here are some of the available P.I.P. modules:
P.I.P.-AMCb unites many features of the P.I.P.-XOV and P.I.P.-CLP. It offers a variable 4th-order Linkwitz-Riley crossover and an IOC-driven, variable threshold com-pressor. In addition, it provides “constant- directivity” horn equalization and filter-assisted B6 vented box equalization. Biamping and tramping capabilities are provided via XLR connectors.
P.I.P.-EDCb combines a sophisticated error-driven com-pressor and smooth limiter with a subsonic filter for each channel. The compressors have adjustable attack and release times, and can be set to track each other. The compressors activate when a signal will clip the input, an IOC error occurs, or the output exceeds the selected threshold. The subsonic filters have corner frequencies of 24, 28, 32 and 36 Hz.
P.I.P.-FTE includes all P.I.P.-FXT features, and adds 12 dB/octave RFI filters, variable 18 dB/octave high-pass filters, and 6 dB/octave 3 kHz shelving networks for “con-stant-directivity” horn equalization. Screw terminal plugs are provided for input.
IQ-P.I.P.-AP integrates the amplifier into Crown’s patented IQ System.® The IQ System provides centralized computer control of 1 to 2,000 amplifiers. Each amplifier channel can be monitored and controlled from an inexpensive personal computer. Any combination of mic-and-line-level signals can also be mixed and routed with optional MPX-6,™ SMX-6™ and AMB-5™ mixer/multiplex-ers, and the MRX series matrixers.
IQ-P.I.P.-AP Smart Amp™ offers the monitoring and control features of the IQ-P.I.P.-AP plus the ability to function as a stand-alone unit as part of the IQ System’s distributed intelligence.™ Features include a smooth output limiter for transparent loudspeaker protection, power supply gates for energy savings, ODEP conservation which protects the output devices with precision input signal control, interrupt-driven report-ing that lets you define error conditions, and config-urable short detection.
P.I.P.-CLP is designed to detect and prevent overload. Its compressor is driven by the amplifier’s built-in IOC error detection circuitry. Unlike typical signal-driven compressors, it only compresses the signal to prevent overload. It can deliver up to 13 dB of additional headroom without being noticeable.
P.I.P.-ISO is designed especially for 25 to 140-volt dis-tributed systems where UL®-listed isolation is required. Installation requires minor amplifier modifications. With the P.I.P.-ISO installed, the amplifier outputs are safely isolated from the input terminals and the chassis.
P.I.P.-ATN includes all P.I.P.-FTE features, plus a 32-step precision attenuator for each channel.
P.I.P.-XOV is a versatile 18 dB/octave mono crossover/filter with biamping and triamping capabilities.
P.I.P.-FMX facilitates “daisy-chaining” balanced amplifier inputs. Female-to-male three-pin XLR connectors are used to passively bridge the inputs.
P.I.P.-FXQ makes it easy to connect audio sources that have phono (RCA) connectors. It includes two balanced three-pin female XLR connectors, and two female phono jacks for quasi-balanced or unbalanced operation.
P.I.P.-FXT uses balanced 1:1 transformers to isolate the amplifier from the input signal. It has balanced female three-pin XLR connectors.
P.I.P.-PA adds a switchable balanced low-impedance mic input, a balanced line-level input and a compressor to each channel. Remote switching circuitry provides quick and quiet fades from mic to line and back.
P.I.P.-102 is a two-channel module providing equalization based on the BOSE® 102 controller. Screw terminal plugs provide balanced connections. Each input channel has an output from the P.I.P. that can be indepen-dently configured for output with no processing, 102 equalizations or 102 equalizations with bass-cut.
P.I.P.-RPA adds the features of a 4×2 mixer to your amplifier. Its four
inputs accept mic- or line-level input. It offers priority switching (“voice-
over”) of each input and remote level control with the RPA-RMT. Other features
include bus inputs and outputs, adjustable input sensitivity, phantom power
and RFI suppression. Input isolation transformers are optional.
For more information on these P.I.P.s or other P.I.P.s under development,
contact your local dealer or Crown’s Technical Support Group.
Service
This unit has very sophisticated circuitry which should only be serviced by a
fully trained technician. This is one reason why each unit bears the following
label:
CAUTION: To prevent electric shock, do not remove covers. No user-
serviceable parts inside. Refer servicing to a qualified technician.
Worldwide Service
Service may be obtained from an authorized service center. (Contact your local
Crown/Amcron representative or our office for a list of authorized service
centers.) To obtain service, simply present the bill of sale as proof of
purchase along with the defective unit to an authorized service center. They
will handle the necessary paperwork and repair.
Remember to transport your unit in the original factory pack. We will pay the
surface shipping costs both ways for warranty service to the authorized
service center nearest you after receiving copies of all shipping receipts.
You must bear the expense of all taxes, duties, and customs fees when
transporting the unit.
North American Service
Service may be obtained in one of two ways: from an authorized service center
or from the factory. You may choose either. It is important that you have your
copy of the bill of sale as your proof of purchase.
Service at a North American Service Center
This method usually saves the most time and effort. Simply present your bill
of sale along with the defective unit to an authorized service center to
obtain service. They will handle the necessary paperwork and repair. Remember
to transport the unit in the original factory pack. A list of authorized
service centers in your area can be obtained from our Technical Support Group.
Factory Service
To obtain factory service, fill out the service information page that follows
and send it along with your proof of purchase and the defective unit to the
Crown factory. For warranty service, we will pay for ground shipping both ways
in the United States after receiving copies of the shipping receipts.
Shipments should be sent “UPS ground.” (If the unit is under warranty, you may
send it C.O.D. for the cost of freight via UPS ground.) The factory will
return it via UPS ground. Please contact us if other arrangements are
required.
Factory Service Shipping Instructions:
- When sending a Crown product to the factory for service, be sure to fill out the service information form that follows and enclose it inside your unit’s shipping pack. Do not send the service information form separately.
- To ensure the safe transportation of your unit to the factory, ship it in an original factory packing container. If you don’t have one, call or write Crown’s Parts Department. With the exception of polyurethane or wooden crates, any other packing material will not be sufficient to withstand the stress of shipping. Do not use loose, small-size packing materials.
- Do not ship the unit in any kind of cabinet (wood or metal). Ignoring this warning may result in extensive damage to the unit and the cabinet. Accessories are not needed—do not send the instruction manual, cables and other hardware.
If you have any questions, please call or write the Crown Technical Support Group.
Crown Factory Service Information
Shipping Address: Crown International, Inc., Factory Service, 57620 C.R. 105,
Elkhart, Indiana 46517 Phone:
1-800-342-6939 or
1-219-294-8200 Fax:
1-219-294-8301
Owner’s Name:
Shipping Address: __ Phone Number:
Model: ____ Serial Number: __ Purchase Date:
NATURE OF PROBLEM
(Be sure to describe the conditions that existed when the problem occurred and
what attempts were made to correct it.)
Other equipment in your system:
If warranty has expired, payment will be:
Cash/Check
VISA
MasterCard
C.O.D.
Card Number: ____
Exp. Date:
Signature: _____
ENCLOSE THIS PORTION WITH THE UNIT. DO NOT MAIL SEPARATELY.
THREE YEAR FULL WARRANTY
WORLDWIDE
-
SUMMARY OF WARRANTY
The Crown Audio Division of Crown International, Inc., 1718 West Mishawaka Road, Elkhart, Indiana 46517-4095 U.S.A. warrants to you, the ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of each NEW Crown1 product, for a period of three (3) years from the date of purchase by the original purchaser (the “warranty period”) that the new Crown product is free of defects in materials and workmanship, and we further warrant the new Crown product regardless of the reason for failure, except as excluded in this Crown Warranty.
Note: If your unit bears the name “Amcron,” please substitute it for the name “Crown” in this warranty. -
ITEMS EXCLUDED FROM THIS CROWN WARRANTY
This Crown Warranty is in effect only for failure of a new Crown product which occurred within the Warranty Period. It does not cover any product which has been damaged because of any intentional misuse, accident, negligence, or loss which is covered under any of your insurance contracts. This Crown Warranty also does not extend to the new Crown product if the serial number has been defaced, altered, or removed. -
WHAT THE WARRANTOR WILL DO
We will remedy any defect, regardless of the reason for failure (except as excluded), by repair, replacement, or refund. We may not elect refund unless you agree, or unless we are unable to provide replacement, and repair is not practical or cannot be timely made. If a refund is elected, then you must make the defective or malfunctioning product available to us free and clear of all liens or other encumbrances. The refund will be equal to the actual purchase price, not including interest, insurance, closing costs, and other finance charges less a reasonable depreciation on the product from the date of original purchase. Warranty work can only be performed at our authorized service centers. We will remedy the defect and ship the product from the service center within a reasonable time after receipt of the defective product at our authorized service center. All expenses in remedying the defect, including surface shipping costs to the nearest authorized service center, will be borne by us. (You must bear the expense of all taxes, duties and other customs fees when transporting the product.) -
HOW TO OBTAIN WARRANTY SERVICE
You must notify us of your need for warranty service not later than ninety (90) days after expiration of the warranty period. All components must be shipped in a factory pack. Corrective action will be taken within a reasonable time of the date of receipt of the defective product by our authorized service center. If the repairs made by our authorized service center are not satisfactory, notify our authorized service center immediately. -
DISCLAIMER OF CONSEQUENTIAL AND INCIDENTAL DAMAGES
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY INCIDENTAL DAMAGES RESULTING FROM ANY DEFECT IN THE NEW CROWN PRODUCT. THIS INCLUDES ANY DAMAGE TO ANOTHER PRODUCT OR PRODUCTS RESULTING FROM SUCH A DEFECT. -
WARRANTY ALTERATIONS
No person has the authority to enlarge, amend, or modify this Crown Warranty. This Crown Warranty is not extended by the length of time which you are deprived of the use of the new Crown product. Repairs and replacement parts provided under the terms of this Crown Warranty shall carry only the unexpired portion of this Crown Warranty. -
DESIGN CHANGES
We reserve the right to change the design of any product from time to time without notice and with no obligation to make corresponding changes in products previously manufactured. -
LEGAL REMEDIES OF PURCHASER
No action to enforce this Crown Warranty shall be commenced later than ninety (90) days after expiration of the warranty period.
THIS STATEMENT OF WARRANTY SUPERSEDES ANY OTHERS CONTAINED IN THIS MANUAL FOR CROWN PRODUCTS.
Telephone: 219-294-8200. Facsimile: 219-294-8301
NORTH AMERICA
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SUMMARY OF WARRANTY
The Crown Audio Division of Crown International, Inc., 1718 West Mishawaka Road, Elkhart, Indiana 46517-4095 U.S.A. warrants to you, the ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of each NEW Crown product, for a period of three (3) years from the date of purchase by the original purchaser (the “warranty period”) that the new Crown product is free of defects in materials and workmanship, and we further warrant the new Crown product regardless of the reason for failure, except as excluded in this Crown Warranty. -
ITEMS EXCLUDED FROM THIS CROWN WARRANTY
This Crown Warranty is in effect only for failure of a new Crown product which occurred within the Warranty Period. It does not cover any product which has been damaged because of any intentional misuse, accident, negligence, or loss which is covered under any of your insurance contracts. This Crown Warranty also does not extend to the new Crown product if the serial number has been defaced, altered, or removed. -
WHAT THE WARRANTOR WILL DO
We will remedy any defect, regardless of the reason for failure (except as excluded), by repair, replacement, or refund. We may not elect refund unless you agree, or unless we are unable to provide replacement, and repair is not practical or cannot be timely made. If a refund is elected, then you must make the defective or malfunctioning product available to us free and clear of all liens or other encumbrances. The refund will be equal to the actual purchase price, not including interest, insurance, closing costs, and other finance charges less a reasonable depreciation on the product from the date of original purchase. Warranty work can only be performed at our authorized service centers or at the factory. We will remedy the defect and ship the product from the service center or our factory within a reasonable time after receipt of the defective product at our authorized service center or our factory. All expenses in remedying the defect, including surface shipping costs in the United States, will be borne by us. (You must bear the expense of shipping the product between any foreign country and the port of entry in the United States and all taxes, duties, and other customs fees for such foreign shipments.) -
HOW TO OBTAIN WARRANTY SERVICE
You must notify us of your need for warranty service not later than ninety (90) days after expiration of the warranty period. All components must be shipped in a factory pack, which, if needed, may be obtained from us free of charge. Corrective action will be taken within a reasonable time of the date of receipt of the defective product by us or our authorized service center. If the repairs made by us or our authorized service center are not satisfactory, notify us or our authorized service center immediately. -
DISCLAIMER OF CONSEQUENTIAL AND INCIDENTAL DAMAGES
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY INCIDENTAL DAMAGES RESULTING FROM ANY DEFECT IN THE NEW CROWN PRODUCT. THIS INCLUDES ANY DAMAGE TO ANOTHER PRODUCT OR PRODUCTS RESULTING FROM SUCH A DEFECT. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATIONS OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU. -
WARRANTY ALTERATIONS
No person has the authority to enlarge, amend, or modify this Crown Warranty. This Crown Warranty is not extended by the length of time which you are deprived of the use of the new Crown product. Repairs and replacement parts provided under the terms of this Crown Warranty shall carry only the unexpired portion of this Crown Warranty. -
DESIGN CHANGES
We reserve the right to change the design of any product from time to time without notice and with no obligation to make corresponding changes in products previously manufactured. -
LEGAL REMEDIES OF PURCHASER
THIS CROWN WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, YOU MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO STATE. No action to enforce this Crown Warranty shall be commenced later than ninety (90) days after expiration of the warranty period. THIS STATEMENT OF WARRANTY SUPERSEDES ANY OTHERS CONTAINED IN THIS MANUAL FOR CROWN PRODUCTS.
Telephone: 219-294-8200. Facsimile: 219-294-8301
©1995 by CROWN INTERNATIONAL, INC.
P.O. Box 1000, Elkhart, Indiana 46515-1000
Telephone: 219-294-8000
Trademark Notice: Studio Reference,™ Smart Amp,™ MPX-6,™ SMX-6,™ AMB-5,™and grounded bridge™ are trademarks and Crown,® IOC®, ODEP,® IQ System ® and P.I.P.® are registered trademarks of Crown International, Inc. Other trademarks are the property of their respective owners.
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